Audio playback devices are becoming more and more important. Particularly, increasing numbers of users buy harddisk-based audio players and other entertainment equipment.
Psycho-acoustic tricks may be used to improve audio playback quality.
EP 0,972,426 discloses an apparatus for conveying a pseudo-low frequency psycho-acoustic sensation of a sound signal to a listener, the apparatus including a frequency unit which is capable of deriving a high-frequency signal and a low-frequency signal from the sound signal within a low-frequency range of interest. A harmonics generator is coupled to the frequency generator and is capable of generating, for each fundamental frequency within the low-frequency range of interest, a residual harmonic signal having a sequence of harmonics. The sequence of harmonics, generated with respect to each fundamental frequency, comprises a first group of harmonics that includes at least three consecutive harmonics from among a primary set of harmonics of the fundamental frequency. A loudness generator is coupled to the harmonics generator and is capable of matching the loudness of the residual harmonic signal with the loudness of the low-frequency signal. A summation unit is capable of summing the residual harmonic signal and the high-frequency signal so as to obtain a psycho-acoustic alternative signal.
However, there are circumstances in which the audio playback quality of the system of EP 0,972,426 is not sufficient.